Method of forming clips

ABSTRACT

A wire clip of noncircular cross section is formed from a length of wire by swaging the wire to the desired noncircular crosssectional shape. The wire is fed intermittently toward a wirecutting and clip-forming device and the swaging step is carried out while the wire is stationary and the clip is being formed.

Unite States Patent Inventor Karl A. Klenz Oakland, Calif. Appl. No. 37,990 Filed May 18, 1970 Patented Dec. 14, I971 Assignee Rheem Manufacturing Company New York, N.Y.

METHOD OF FORMING CLIPS 2 Claims, 3 Drawing Figs.

11.8. C1 140/82, 72/337, 72/384, 72/405 Int. Cl B2lf 45/22 Field of Search 140/ 1, 2,

[56] References Cited UNITED STATES PATENTS 418,145 12/1889 Taylor 72/338 1,220,835 3/1917 Forbes 72/404 Primary Examiner-Lowe1l A. Larson Attorney-Gordon Wood ABSTRACT: A wire clip of noncircular cross section is formed from a length of wire by swaging the wire to the desired noncircular cross-sectional shape. The wire is fed intermittently toward a wire-cutting and cEIip-forming device and the swaging step is carried out while the wire is stationary and the clip is being formed.

PATENTEU BECMIQH 3 25 994 INVENTOR. KAR L. A. KLENZ METHOD OF FORMING CLIPS This invention relates to a method of forming U-shaped clips of the type shown in US. Pat No 3,400,433. This type of clip is employed for tying flexible containers such as bags, sausage casings and the like and, as pointed out in the referenced patent, certain advantages accrue from forming the U-shaped clip from wire which does not have a circular cross section but which is specially shaped to minimize damage to the material to be sealed and at the same time provide optimum strength. Although the particular wire cross section shown in the above noted patent will be used as an example in this disclosure it will be apparent that the present invention is applicable to any clip-forming operation regardless of the particular noncircular cross section employed.

In manufacturing clips of the subject type the customary procedure is for the manufacturer to purchase reels of wire from a wire supplier. In some instances the wire may be formed to a particular cross section to meet the users specification but, in any event, the usual procedure is for the manufacturer to make the wire to the desired shape by drawing the same through a die in a manner that is well known. One of the results of such a drawing process is that the wire develops a twist which makes it unwiedly to handle. However, if the wire is of circular cross section there is not particular orientation of the same required relative to its cross section. When a special cross section is desired such as the one shown in the cited patent the inherent tendency for the drawn wire to twist creates many problems, the greatest one being that of orienting the wire with the noncircular cross section in a predetermined position relative to the clip-forming means so that all the clips are identical Another problem is that the twisted wire is more likely to be damaged in handling. Furthermore, the required orientation requires special equipment which is unnecessary in the case of circular wire.

The main object of the present invention is the provision of a method of forming clips from wire of a noncircular cross section and which method obviates the disadvantages of prior art methods presently available.

Another object of the invention is the provision of a method of forming U-shaped clips of noncircular cross section which permits the use of a compact arrangement of equipment to perform the step of shaping the wire to the noncircular cross section.

Another object of the invention is the provision of a method for forming U-shaped clips of noncircular cross section which results in a considerable saving and expense over the prior art method of purchasing the wire from a wire manufacturer to the user's specification.

Still another object of the invention is the provision of a method for forming U-shaped clips from wire of noncircular cross section which has the advantage of permitting the provision of an improved product with an extremely good surface finish.

Other objects and advantages will be apparent from the following specification and from the drawing:

FIG. I is a side elevation of a clip-forming press showing the wire feeding and shaping means at one side thereof.

FIG. 2 is a horizontal section taken in the plane indicated by lines 2-2 of FIG. 1.

FIG. 3 is a greatly enlarged fragmentary cross section taken through the swagging dies when the same are in their abutting position.

The present method of forming U-shaped clips from a length of wire, whether the wire be of circular or noncircular cross section, is to feed the wire intermittently into a press provided with a wirecutting punch which cuts off a short length of the wire and, in one operation, bends the cut portion around an anvil to form the U-shaped clip.

Such a press is shown in FIG. 1 and, in general, includes a ram 2 at the lower end of the connecting rod 3 which is oscillatably mounted at its upper end on an eccentric portion of main shaft 4 which is provided with a flywheel (not shown) driven by any suitable source of power. Secured to ram 2 is an upper die shoe 8 which is vertically slidable along a pair of vertically extending posts 9 and which has secured thereto a downwardly extending punch 10. A lower die shoe 12 is fixed to the base 113 of the press nd fixedly secured to said die shoe I2 is a clip-forming rail 15 which is provided with a curved upper edge around which the wire is bent to form the U- shaped clip. Said rail extends horizontally outwardly from die shoe 12 and the completed clips 16 are fed along the length of said rail as shown in FIG. 2 to the clip packaging operation.

In the particular arrangement shown in FIGS. 1 and 2, two wires 20 and 21 are simultaneously fed toward the press from the left hand side thereof and two wires 22 and 23 are fed by similar apparatus from the right hand side. Only one complete side is shown in the drawings. However, from FIG. 2 it will be apparent that the wires are staggered so that upon one reciprocation of the punch four wires are cut and four clips formed simultaneously.

The wires are fed to the punch through dies 24 in an upstanding portion 25 of a cutoff block generally designated 26. The upper surface of the cutoff block is formed with grooves 27, 28 for receiving the wires 20, 21 respectively prior to their passage through dies 24. By a means which will be described later on the wire is intennittently fed on each cycle a distance substantially equal to the spacing between the upstanding portions 25 of the two cutoff blocks so that as the punch 10 is urged downwardly from its upper position of FIG. 1 the four wires 20 to 23 are cut. Upon further downward movement of the punch 10 the ends of the cut wires are bent around the top of rail 15 by a recessed portion 30 at the lower end of punch 10. The final step in the clip-forming operation is performed when the' bottom of the recess 30 engages a stripper plate 31 and forces the same against the crown of the formed clip thereby setting" the bent clip to an almost perfect U-shaped. The stripper plate 31 is formed as shown in FIG. 2 and is yieldably supported on three upstanding studs 32 on die shoe 12. The stripper plate 31 is urged to its upper position by compression springs 33. It will be understood that the stripper plate 31 also functions to prevent the punch 10 from dragging the clips upwardly on its return stroke.

Upon each cycle of the mechanism a clip ejector 35 connected by a linkage to the upper and lower die shoes is translated along the length of rail 15 thereby ejecting the clips from the rail-forming station and moving them with the already formed clips along the length of rail 15.

The above described structure is conventional and no claim is made thereto except in combination with the method and apparatus herein claimed.

The wires 20, 21 are initially reeled around drums 40 which are rotatably supported on rollers to permit the wires to be fed off the drums upon the imposition of a slight tension. The wires 20, 21 as they come from drums 40 may be conventional wire of circular cross section and are first passed through a block 41 provided with passageways for receiving the wires 20, 2] therethrough so that the wires will be substantially straight as they approach the next operation. The swagging operation is performed by a pair of dies; a lower fixed die 37 and an upper reciprocating die 38. The reciprocating die 38 may be actuated by a punch generally designated 39 which may be similar to the press employed for forming the U- shaped clips and may in fact be operated from the same shaft 4 which drives the clip-forming press.

The length of dies 37, 38 is at least equal to but preferably slightly longer than the length of wire required to form a clip. In this way the wire is shaped to the desired noncircular cross section throughout its entire length.

The intermittent feeding of the wire is accomplished by a pair of upper and lower feed rolls 42, 43 respectively that are keyed to upper and lower shafts 44, 45. These shafts are rotatably supported in a support 47 fixedly secured to the base of the punch press 39.

On one side of the apparatus each shaft 44, 45 is provided with an overrunning clutch 50 which is designed to permit free rotation in one direction and to prevent any rotation in the reverse direction. The lower shaft 45 is provided with a crank arm 52 which is pivotally connected at its outer end to a generally vertically extending connecting rod 53 which in turn is pivotally connected at its upper end to an eccentric 54 carried by a portion of main shaft 4 of press 1. By this structure upon each rotation of main shaft 4, representing a cycle, shaft 45 is oscillated a predetermined number of degrees. This oscillation is transferred through spur gears 58 to the upper shaft 44 so that both shafts undergo the same degree of turn upon each cycle. The overrunning clutches 50 permit rotation of shafts 44, 45 only in the feeding direction. It will be understood that the pressure applied by feed rolls 42, 43 is not sufficient to deform the wire but is great enough to effect the desired feeding. Preferably the rolls 42, 43 are formed with peripherally extending grooves of a shape complimentary to the shape of the swaged wire so as to obtain as much area of contact as possible.

From the above description it will be seen that only rolls 42, 43 are required to efi'ect the desired intermittent feeding movement and it will be understood that during the short period of time when the wire is stationary both the swagging step perfon'ned by dies 37, 38 and the clip cutting and forming steps performed by the clip-forming press take place.

In FIG. 3 cooperating portions of dies 37, 38 are shown in their abutting position, in which position the wire is formed to the desired shape by grooves 50, 51 formed respectively in said dies 37, 38. I

Not only does the above described method of swagging the wire immediately prior to the cutting the forming steps obviate the difficulty of orienting a preformed wire but the swagging of the wire by dies 37, 38 results in a polishing operation as the area of the wire is changed. A clean burnished surface of wire therefore immediately results prior to the clip-forming step so that the finished clips may be packaged before exposure to the atmosphere adversely effects the surface.

The above described method of forming U-shaped clips of noncircular cross section is particularly adapted to use in situations where the quantity of clips to be manufactured is not sufficiently great to justify the use of more expensive form rolls.

I claim:

1. The method of making a U-shaped clip of noncircular cross section comprising the steps of:

providing a length of wire,

feeding said wire intermittently lengthwise to a wire cutting and forming means,

swagging a section of said wire to such noncircular cross section while said wire is stationary with said section being of a length at least equal to the length of wire required to form a clip,

cutting a length of the swaged wire and forming it to a U- shaped clip while said swagging step is being performed on a trailing section of the wire.

2. The method of claim 1 wherein said swagging step is performed by a pair of relatively movable dies.

t i i I? 

1. The method of making a U-shaped clip of noncircular cross section comprising the steps of: providing a length of wire, feeding said wire intermittently lengthwise to a wire cutting and forming means, swagging a section of said wire to such noncircular cross section while said wire is stationary with said section being of a length at least equal to the length of wire required to form a clip, cutting a length of the swaged wire and forming it to a U-shaped clip while said swagging step is being performed on a trailing sEction of the wire.
 2. The method of claim 1 wherein said swagging step is performed by a pair of relatively movable dies. 